This invention is related to the above-described application and to an earlier filed co-pending application Ser. No. 456,860, filed Jan. 10, 1983, now U.S. Pat. No. 4,522,128, entitled Switch Mechanism; and earlier filed copending application Ser. No. 741,567, filed June 5, 1985 entitled SWITCH MECHANISM by J. Edward Anderson and Robert A. Sells, all of which are assigned to the Regents of the University of Minnesota.
With the increase in fuel costs and escalating construction costs for automobile-type surface roads, the need for fuel efficient, economical rapid transit has increased. The state of mass transit at present includes surface buses and surface railway systems as well as underground subway trains and elevated trains and the like. All of these systems attempt to move large numbers of people in large vehicles.
Consequently, the vehicle must stop at a plurality of stations to allow passengers to embark and disembark as desired. Therefore, the effective average speed of the vehicle is reduced by constant stopping and starting, and most riders make numerous stops between the point they get on the vehicle and their intended destination.
A personal rapid transit system would eliminate several of these problems as each vehicle carries a small number of passengers desiring to go to the same destination, and each vehicle bypasses all intermediate stops. Therefore, the average speed of the vehicle can be greatly increased while its maximum speed remains the same, and delays associated with stopping at intermediate points are eliminated. The advantages of this design have been known to those skilled in the art, but the construction of a guideway system which could be constructed economically and which was durable enough to be practical has eluded those in the art.
General background information on transit systems can be found in the Journal of Advanced Transportation, specifically volume 15, No. 2 dated Summer, 1981; Fundamentals of Personal Rapid Transit by Jack H. Irving, Ph.D., published in 1978 by D. C. Health and Co., Lexington, Mass.; and Environment, specifically Volume 22, No. 8, dated October, 1980, which includes an article entitled "Personal Rapid Transit". Additional information on this subject can be found in the books Personal Rapid Transit I, Personal Rapid Transit II and Personal Rapid Transit III published at the University of Minnesota, Minneapolis, Minn., in April 1972, February 1974, and June 1976, respectively.
The elimination of the requirement that a vehicle stop at all intermediate points generally requires that all stopping points be wayside stations or be located on sidings or similarly removed from the main track so that stopped vehicles do not hinder the passage of through vehicles. Therefore, the construction of a track or guideway for this type of system is challenging.
The construction of a guideway system supported above the ground offers several advantages to track systems located either on the ground or below ground. The below ground system offers the obvious disadvantage of requiring tunneling or other expensive right-of-way preparation. Surface tracks also require substantial site grading and right-of-way preparation, and lead to annoying vibration transmitted to nearby structures and people. Grade level tracks are also dangerous to cross traffic and require crossing gates and safety lights. An elevated guideway offers obvious advantages, but the construction of an elevated guideway suitable for use with a personal rapid transit system is challenging.
The problems associated with an above ground installation for a guideway system having wayside stations are numerous, and include the problems associated with harmonic oscillation of the guideway as vehicles pass along its length. The construction of a lightweight guideway strong enough to support a number of individual vehicles passing at moderate or rapid speeds poses a serious oscillation problem. Damping of harmonic oscillation frequencies generally requires an increased guideway mass which further complicates the oscillation problem and increases the cost of the guideway.
It is also desirable to construct the guideway in a prefabricated manner to save on construction and erection costs. Typically, prefabricated guideways suffer from their inability to cope with oscillation. This problem is exacerbated by the typical construction which places guideway supporting posts beneath the ends of each guideway section so that the point of support of each section is the same as its point of attachment to adjacent guideway sections. This construction design causes the center of each guideway section to oscillate with the guideway support posts functioning as node points in the oscillation wave along the length of the guideway.
Oscillation of the guideway creates numerous problems including the requirement for reinforcement structures along the guideway, thereby increasing the guideway's weight and cost. When the weight of the guideway is increased, the oscillation mass is also increased thereby aggrevating the problem. Additionally, oscillation of the guideway greatly detracts from ride comfort within the vehicle, and accelerates wear of the guideway itself caused by flexing. For example, U.S. Pat. No. 3,225,703 issued Dec. 28, 1965 illustrates a device having beams affixed at their ends to support columns. This type of device includes dash pot like devices to manage force transmission between adjacent beams.
As the success of the rapid transit system depends directly on the confidence its ridership has in the functioning and structure of the system, the elimination of oscillation and its associated problems is critical to the construction of an economically feasible and viable guideway and transportation system.